Re: Looking for DECstation 3100/2100 or DECsystem 5100

["Maciej W. Rozycki" <macro%linux-mips.org@localhost>]

On Mon, 14 Aug 2017, Felix Deichmann wrote:

> FWIW, this is harder to do for the DS3100 (but still possible). The
> DS3100 KN01-AA board and H7821 PSU use a 14-pos. Molex Mini-Fit Jr.
> (an "ATX 14-pos. variant" connector if you want) with the following
> pin-out:
> 
> 1   -12V    (blue)
> 2   GND     (black)
> 3   GND     (black)
> 4   GND     (black)
> 5   +5.1V   (red)
> 6   +5.1V   (red)
> 7   PWROK   (brown)
> 8   +5.1V   (red)
> 9   +12V    (orange)
> 10  +5.1V   (red)
> 11  GND     (black)
> 12  GND     (black)
> 13  -9V     (yellow)    \  probably
> 14  -9V ret (white)     /  isolated!
> 
> PWROK is active-high (5V logic) and thus directly compatible with the
> ATX PWROK output. The power rails referenced to GND (excluding -9V)
> should also be compatible. The hard part is deriving a probably
> *isolated* -9V rail for which no ATX equivalent exists! I think this
> is used for 10BASE2 ethernet. So re-using a 5V-->9V isolated DC/DC
> converter from an old BNC network card could do the trick (tip from
> http://www.sprut.de/electronic/switch/smallup/smallup.html#5vto9v).

 It is isolated indeed, according to documentation available[1].  I think 
I've come across a second pinout reference, but cannot track it down right 
now.

> However, most VAXstations 3100 also use the H7821, so it could be
> easier to find one there before starting to tinker...

 As do the ubiquitous SZ12 storage expansion boxes (and anything housed 
in a BA42 enclosure).

 I've checked the battery and the replacement I used is an Infapower T006 
<http://www.infapower.com/t006.html>, which is a 600mAh part compared to 
original (IIRC) 540mAh.  It has a JST EHR-2 connector rather than Molex 
5051, however the pitch is the same (0.1") and the plug fits with no fuss. 
Maplin has it in store as well as online 
<https://www.maplin.co.uk/p/aaa-36v-600mah-cordless-telephone-batteries-3-pack-vw31j>, 
however they do not ship overseas.

References:

[1] "VAXstation 3100 Model 76 Maintenance Guide", Digital Equipment 
    Corporation, Order Number EK-VS31M-MG.002, Second Edition, May 1991, 
    Table 2-3 "System Module Power Connector Voltages", p. 18
    <http://vt100.net/mirror/mds-199909/cd1/vax/vs31mmg2.pdf>

  Maciej